Dredging apparatus with surge compensating means

ABSTRACT

A dredging system including a floating vessel, a ladder pivotally connected to the vessel and capable of being lowered to selected angular positions with respect to the vessel, an excavator at the free end of the ladder for digging and removing material, and a surge compensator on the ladder for adjusting the length of the ladder in response to changes in distance between the vessel and the material being dredged.

United States Patent COMPENSATING MEANS FOREIGN f f ENTS 8 Clai 5 D i Fi 851,333 10/1960 Great Br|tam................

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[54] DREDGING APPARATUS WITH SURGE sator on the ladder for adjusting the length of the ladder in re sponse to changes in and a surge compen removing material,

distance between the vessel and the material being dredged.

9/1900 Robinson 3/1905 Macdonell..... 2/1906 PATENTED W25 I97! SHEET 3 BF 2 INVENTOR ROBERT cl IA/V725 MEANS The invention relates generally to a dredging apparatus for dredging alluvial deposits from the bed beneath a body of water while maintaining a constant force between the digging portion of the apparatus and the bed regardless of the motion of the floating portion of the apparatus.

Dredges having digging means supported by a ladder pivotally connected to the floating portion of the vessel in combination with a suction pipe secured to the ladder for removing the material loosened by the digging means are known to the prior art. In such systems the ladder is normally pivotally lowered until the digging means contacts the bed and operations are then commenced. Since the amount of contact force between the bed and the digging means, once the latter is emplaced, depends upon the position of the floating vessel, surface movement by the vessel hampers the efficiency of the digging operation. Movement of the vessel downwardly toward the bed increases the contact force while movement upwardly decreases the same. It is a primary object of this invention to overcome the aforementioned problem by providing an apparatus which has a compensating means on the dredging ladder to isolate movement of the surface vessel therefrom.

Another important object of the invention is to provide a dredging apparatus having an articulated ladder which is selfadjusting to compensate for variance in the distance between the surface vessel and the water body bed such that the digging means will engage the bed with a substantially constant force.

A yet further object of the invention is to provide a dredging apparatus having a plurality of digging buckets rotatable about a common axis each of which successively captures an amount of material from the bed and individually deliversit to a suction removal means.

A still further object of the invention is to provide a dredging apparatus having a suction removal means adapted to articulate and telescope in order to compensate for the movement of a supporting self-adjusting ladder.

These and other objects of the invention will become more apparent to those skilled in the art by reference to the following detailed description when viewed in light of the accompanying drawings, wherein:

FIG. 1 is a side elevational view of the dredging apparatus with a portion in section and with the operative position of the ladder and associated elements shown in phantom;

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a side elevational view of the dredging apparatus in operation from a particular water level;

FIG. 4 is the same as FIG. 3 but with a higher water level; and

FIG. 5 is the same as FIG. 3 but with a lower water level.

Referring now to the drawings, the numeral generally indicates the apparatus of this invention. A barge or vessel 12 floating on the surface of a body of water 14 is provided in its bow with a well or cut out portion 16. A boom or ladder 18 has its inner end pivotally mounted in the well 16 to trunnions 20 and its outer or free end extends outwardly of the barge for movement from its inoperative position as shown by solid lines in FIG. 1 to its operating position shown in phantom. At its outer end, the ladder carries a digger 22 which will be described in greater detail hereinafter. Raising and lowering of the digger about the axis of the trunnions 20 is accomplished by means of a sheave and cable assembly 24 supported by a framework 26. The framework 26 extends upwardly and outwardly of the vessel to a point generally above the anchor blocks 28 which are secured to midportions of the ladder 18. The cables C thereof are controlled by conventional winch drums W mounted on the vessels deck.

The ladder 18, while supported by the framework 26 via the sheave and cable assembly 24 is itself essentially a supporting structure and is comprised of a pair of suitable braced longitudinal beams 30. Intermediate the length of the boom and more struts 36 at 37 and 37'. The legs34 are also braced by necessary cross members and a connecting plate 38. Through the above construction, there is provided 1 two ladder sections which are always parallel to but translatable lineally from each other. The parallelogram structure 32 is hereinafter separately referred to as a parallelogram compensator.

ln order to limit the amount of collapse,,i.e. pivotal movement of the struts 36 with respect tothe beams 30 and 34, constant tension is applied to the parallelogram compensator by means of a cable and sheave assembly 40. A wire rope 42 is connected at one-end to an air-over-hydraulic piston compensator 44 which is known to those skilled in the artand which is located on the vessel 12. The piston compensator maintains a constant tension on the parallelogram 32 via the cable 42 which passes around sheaves S-1 and S-2 to an anchor 46 on the beam 30. The sheave S-l is located onthe outer end of the beam 30 adjacent the pivot point of the outer strut 36 while the sheave S-2 is located on the inner end of the leg 34 adjacent the inner strut 36. The end of the cable 42 is rigidly connected to the beam 30 by means of the anchor 46.

verse shaft 52. The bucket wheel 22 includes a collar or plate 56 which is rigidly secured to the shaft 52 for rotation therewith. The plate is provided with a series of circumferentially spaced buckets 58 rigidly secured to its outer periphery. Each bucket is cup shaped and has a pair of sidewalls 60 and a bottom wall 62 so that it is open at its top and its rear portions. The buckets 58 are rigidly secured by a weld between the inner edge of one sidewall 60 and the outer periphery of the plate 56. The buckets are preferably made of cast manganese steel and are provided with removable lips on their cutting edge so as to afford quick and easy replacement thereof.

In order to rotate the bucket wheel, two pairs of hydraulic motors are mounted on waterproof housings 64 on the upper and lower surfaces of the offset leg 34 nearest the plate 56. Each pair of motors coacts with a single output shaft 66 on which there is fixed a driving gear 68. Each driving gear 68 meshes with a ring gear 70 which is rigidly and concentrically mounted against the plate 56. The gears 68 and 70 are of a material which is suitable for prolonged operation in sea water.

The suction pipe 50 extends from the vessel 12 along the ladder 18 to which it is rigidly secured. The pipe is comprised, in the main, of a plurality of rigid sections 72 which are joined together end to end. ln-order to adjust for pivotal movement of the ladder 18, a resilient and flexible pipe section 74 of suitable material such as synthetic plastic or rubber is provided at that portion of the pipeline 50 which traversesthe pivot axis of the trunnions 20. Special provisions in the pipeline are made to withstand the movements in the parallelogram surge compensator 32. A pair of universal ball and socket type connections 76 and 76' connect opposite ends of freely telescoping pipe sections 78 and 78 which traverse the parallelogram 32. The inner connection 76 is located without the parallelogram 32 and pivotally secures the pipe section 78 to that portion of the pipeline which is supported from the vessel 12 by the beams 30 while the outer connection 76' is located within the parallelogram 32 and pivotally secures the pipe section 78' to the end portion of the pipeline which is supported by offset legs 34.

The terminal portion of the pipeline 50 is located within the peripheral confines of the bucket wheel 22 and includes an enlarged suction nozzle 80 having a mouth 82 arcuately shaped to closely conform with an arc of the circle described by the open rear portion of the revolving buckets 58. The nozzle 80 is stationary and is large enough to span the open rear portion of at least two of the buckets. As the buckets dig and capture material from the sea bed, they successively pass by the nozzle so that the material is sucked out through their open rear portion.

In the operation of the main components of the dredging apparatus the vessel is positioned as shown in FIG. 1. the

ladder 18 is lowered to the dotted line position until the bucket wheel 22 rests on the sea bed. The desired contact force between the bucket wheel and sea bed is then selected and supplied by applying and maintaining a certain amount of tension to the cable 42 by means of the piston compensator. Excavation is then commenced and during its course, should the vessel rise or fall with the water surface, the ladder will automatically adjust to maintain a substantially constant digging force between the bucket wheel 22 and the bed. If the vessel rises as in FIG. 4, the force on the cable 42 will collapse the parallelogram 32 and thereby extend the ladder 18. If the vessel falls, the amount of tension in the cable 42 extending the ladder 18 is overcome and the ladder is contracted with the aid of the tension spring 48.

in a general manner, while there has been disclosed an effective and efficient embodiment of the invention, it should be well understood that the invention is not limited to such embodiment, as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

lclaim: 1. Apparatus for dredging material from the bed beneath a body of water comprising:

a vessel floating on said body of water; an elongated ladder, said ladder comprising a first ladder section having an inner end pivotally connected to said vessel and having an outer end extending over the water; a second ladder section offset from and parallel to said first ladder section; connection means pivotally connecting said second ladder section to said outer end for parallel, lineal displacement of said second ladder section with respect to said first ladder section;

supporting means connected to said first ladder section between said inner end and said outer end for positioning said ladder at a selected angular position with respect to said vessel;

excavating means carried by said second ladder section for digging and removing material from said bed; and

control means for adjusting the effective combined length of said ladder by lineally displacing said second ladder section with respect to said first ladder section.

2. The invention of claim 1 wherein said excavating means comprises rotatable bucket means for loosening and capturing material from said bed, and suction pipe means supported on said first and second ladder sections for removing said material from said bucket means.

3. The invention of claim 2 wherein flexible means intermediate the length of said suction pipe means permits said pipe means to follow therelative movements between said first and second ladder sections.

4. The invention as described in claim 2 wherein said rotatable bucket means comprises a plurality of buckets open at their inner ends and rotatably disposed to successively present said inner ends to said suction pipe means.

5. The invention as described in claim 4 wherein said suction pipe means is supported on said ladder and comprises a plurality of pipe sections connected together and extending from said vessel to a point adjacent the line of travel circumscribed b the inner end of said buckets, said pipe sections extending t e length of said ladder and being pivotally and telescopically disposed for movement therewith.

6. The invention of claim 1 wherein said connection means comprises a pair of parallel struts pivotally connected at each end to said outer end and said second ladder section and forming a parallelogram therewith.

7. The invention of claim 6 wherein said control means comprises a cable between a pair of diagonally opposite corners of said parallelogram, means to apply a force on said cable to draw said comers toward one another to thus urge collapse of the parallelogram structure and consequent extension of the ladder, and biasing means for urging said comers away from each other.

8. The invention as described in claim 1 wherein said supporting means comprises a framework on said vessel, sheave and cable means connected between said framework and said ladder for raising and lowering said ladder. 

1. Apparatus for dredging material from the bed beneath a body of water comprising: a vessel floating on said body of water; an elongated ladder, said ladder comprising a first ladder section having an inner end pivotally connected to said vessel and having an outer end extending over the water; a second ladder section offset from and parallel to said first ladder section; connection means pivotally connecting said second ladder section to said outer end for parallel, Lineal displacement of said second ladder section with respect to said first ladder section; supporting means connected to said first ladder section between said inner end and said outer end for positioning said ladder at a selected angular position with respect to said vessel; excavating means carried by said second ladder section for digging and removing material from said bed; and control means for adjusting the effective combined length of said ladder by lineally displacing said second ladder section with respect to said first ladder section.
 2. The invention of claim 1 wherein said excavating means comprises rotatable bucket means for loosening and capturing material from said bed, and suction pipe means supported on said first and second ladder sections for removing said material from said bucket means.
 3. The invention of claim 2 wherein flexible means intermediate the length of said suction pipe means permits said pipe means to follow the relative movements between said first and second ladder sections.
 4. The invention as described in claim 2 wherein said rotatable bucket means comprises a plurality of buckets open at their inner ends and rotatably disposed to successively present said inner ends to said suction pipe means.
 5. The invention as described in claim 4 wherein said suction pipe means is supported on said ladder and comprises a plurality of pipe sections connected together and extending from said vessel to a point adjacent the line of travel circumscribed by the inner end of said buckets, said pipe sections extending the length of said ladder and being pivotally and telescopically disposed for movement therewith.
 6. The invention of claim 1 wherein said connection means comprises a pair of parallel struts pivotally connected at each end to said outer end and said second ladder section and forming a parallelogram therewith.
 7. The invention of claim 6 wherein said control means comprises a cable between a pair of diagonally opposite corners of said parallelogram, means to apply a force on said cable to draw said corners toward one another to thus urge collapse of the parallelogram structure and consequent extension of the ladder, and biasing means for urging said corners away from each other.
 8. The invention as described in claim 1 wherein said supporting means comprises a framework on said vessel, sheave and cable means connected between said framework and said ladder for raising and lowering said ladder. 